Stormwater Management Practices

Exhibit A Operations and Maintenance Plan (Property Address) (Date)

Scope:

The purpose of the Operations and Maintenance Plan is to ensure that the existing and proposed stormwater components installed at (Property Address) are maintained in operational condition throughout the life of the project. The service procedures associated with this plan shall be performed as required by the parties legally responsible for their maintenance.

Recommended Frequency of Service:

As further defined below, all stormwater components should be checked on a periodic basis and kept in full working order. Ultimately, the required frequency of inspection and service will depend on runoff quantities, pollutant loading, and clogging due to debris. At a minimum, we recommend that all stormwater components be inspected and serviced twice per year, once before winter begins and once during spring cleanup.

Qualified Inspector:

The inspections must be completed by an individual experienced in the construction and maintenance of stormwater drainage systems. Once every five years the inspections must be completed by a professional engineer.

Service Procedures:

1. Catch Basins & Drainage Inlets:

a. Catch basins and drainage inlets shall be completely cleaned of accumulated debris and sediments at the completion of construction. b. For the first year, catch basins and drainage inlets shall be inspected on a quarterly basis. c. Any accumulated debris within the catch basins/inlets shall be removed and any repairs as required. d. From the second year onward, visual inspections shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris within the catch basins/inlets shall be removed and repairs made as required. f. Accumulated sediments shall be removed at which time they are within 12 inches of the invert of the outlet pipe. g. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

2. Storm Drainage Piping and Manholes/Junction Boxes:

a. All storm drainage piping shall be completely flushed of debris and accumulated sediment at the completion of construction. b. Manholes/Junction Boxes shall be inspected and repaired on an annual basis.

Form MD-100 February 2014 c. Unless system performance indicates degradation of piping, comprehensive video inspection of storm drainage piping shall occur once every ten years. d. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

3. Stormwater Control Structures:

a. All control structures (orifice, weir, etc.) shall be completely cleaned of accumulated debris and sediments at the completion of construction. Any repairs shall be performed. b. For the first year, control structures (orifice, weir, etc.) shall be inspected on a quarterly basis. c. Any accumulated debris shall be removed and any repairs made to the control structures (orifice, weir, etc.) as required. d. From the second year onward, visual inspections shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris shall be removed and repairs made as required. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

4. Hydrodynamic Separator:

a. Hydrodynamic Separator shall be completely cleaned of accumulated debris and sediments at the completion of construction. b. For the first year, the hydrodynamic separator shall be inspected on a quarterly basis. c. Any accumulated debris within the hydrodynamic separator shall be removed and any repairs made to the unit as required. d. From the second year onward, visual inspection shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris within the unit shall be removed and repairs made as required. f. Accumulated sediments shall be removed at which time they are within 12 inches of the invert of the outlet pipe. g. All inlets, outlets and components of the unit shall be inspected and cleared of debris. Any repairs shall be performed. h. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

5. Drainage Outfalls/Splash Pads/Scour Holes/Level Spreaders:

a. All outfalls shall be completely cleaned of accumulated debris and sediments at the completion of construction. Any repairs to outlet protection material (rip rap) shall be performed. b. For the first year, outfalls shall be inspected on a quarterly basis. c. Any accumulated debris shall be removed and any repairs made to the outfalls as required. d. From the second year onward, visual inspections shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris shall be removed and repairs made as required. f. Any erosion shall be promptly repaired and the cause of the erosion shall be identified and corrected. g. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

Form MD-100 February 2014 6. Bioretention/Biofiltration Basins and Rain Gardens:

a. Bioretention/Biofiltration basins and rain gardens shall be cleaned of debris and sediments upon the completion of construction. Any filter media (bioretention soil) impacted by the construction activities shall be removed and replaced at this time. b. The filter media (bioretention soil) shall be visually inspected on a monthly basis for the first 6 months. Any erosion or displacement of the filter media (bioretention soil) shall be promptly repaired and the cause of the problem shall be identified and corrected. Monthly inspections shall continue until successful operation of the system is confirmed. c. Bioretention/Biofiltration areas and rain gardens with grass shall not be mowed more than twice during the growing season, preferably only in late October. More frequent mowing will eliminate native forbs and sedges from the meadow cover. d. Bioretention/Biofiltration areas and rain gardens with mulch and plantings shall be inspected during spring cleanup and one just prior to the winter season. e. All dead plants and missing mulch shall be replaced and any necessary pruning of vegetation shall be completed. f. The surface of these structures shall be inspected on a quarterly basis after the first six months of successful operation and after heavy runoff events (e.g. >3.0” in a 24-hour period). One inspection shall occur immediately following the completion of winter sanding and subsequent sweeping operations, and one shall occur just prior to the winter season. Any accumulated debris and sediments shall be removed. g. Check draining time of bioretention/biofiltration areas and rain gardens annually. Check within 72 hours after a minimum one inch rain event. If there is no standing water, infiltration is acceptable. If draining time is excessive, quantitatively determine infiltration rate. Use a double ring infiltrometer or monitor drop in water level after a significant storm. If infiltration rate <0.5 in. /hour, remedial action shall be taken. h. A soil-core investigation may be used to identify the clogged portion of stormwater facility and depth of clogging. Remedial measures may include removal of clogged soil layer and replacement with suitable media, aeration, and mixing upper strata with lower soil strata. After corrective measures have been implemented, infiltration rate and draining time shall be retested.

7. Drywells and Infiltration Systems:

a. All drywells/infiltrators shall be completely cleaned of accumulated debris and sediments upon the completion of construction. b. For the first year, the drywells/infiltrators shall be inspected on a quarterly basis. c. Any accumulated debris within the drywells/infiltrators shall be removed and any repairs made to the units as required. d. From the second year onward, visual inspection shall occur twice per year, once in the spring and once in the fall, after fall cleanup of leaves has occurred. e. Accumulated debris within the units shall be removed and repairs made as required. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

8. Porous Pavement (Pervious Concrete, Porous Asphalt, Permeable Interlocking Concrete Pavers, Flexi pave, Etc.):

a. Changing the porous pavement surface to an impervious surface requires the review and approval of the Town of Greenwich DPW Engineering Division. b. Clean and vacuum (Regenerative Air Vacuum for Permeable Interlocking Concrete Pavers) the porous pavement upon the completion of construction.

Form MD-100 February 2014 c. Check for standing water on the surface of the pavement after a precipitation event. If standing water remains within 30 minutes after rainfall had ended, cleaning of porous pavement is recommended. d. Vacuum sweeper shall be used regularly to remove sediment and organic debris on the pavement surface. The sweeper may be fitted with water jets. e. Pavement vacuuming should occur during spring cleanup following the last snow event to remove accumulated debris, at a minimum. f. Pavement vacuuming should occur during fall cleanup to remove dead leaves, at a minimum. g. Power washing can be an effective tool for cleaning clogged areas. See manufacturer’s specifications. h. Check for debris accumulating on pavement, especially debris buildup in winter. For loose debris, a power/leaf blower or gutter broom can be used to remove leaves and trash. i. In the event that the porous surface becomes clogged an engineer must be retained to determine how to restore the porous surface to its original condition. j. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

9. Gravel Pavement (Gravel Driveway with Gravel Pave 2 (Or Approved Equal):

a. Changing the gravel pavement surface to an impervious surface requires the review and approval of the Town of Greenwich DPW Engineering Division. b. Clean upon the completion of construction. c. The gravel pavement shall be graded and additional gravel added as needed during spring and fall cleanup. d. Check for standing water on the surface of the gravel pavement after a precipitation event. If standing water remains within 30 minutes after rainfall had ended, repair to the gravel pavement is recommended. e. In the event that the gravel pavement surface becomes clogged an engineer must be retained to determine how to restore the gravel pavement surface to its original condition. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

10. Vegetative Roof:

a. Vegetative roof shall be cleaned of debris and sediments upon the completion of construction. Any filter media impacted by the construction activities shall be removed and replaced at this time. b. The roof shall be visually inspected on a bi-weekly basis for the first 6 months. Any erosion or displacement of the filter media shall be promptly repaired and the cause of the problem shall be identified and corrected. During these inspections weeds shall be pulled and removed. Monthly inspections shall continue until successful operation of the system is confirmed. c. The surface of these structures shall be inspected on a quarterly basis after the first six months of successful operation and after heavy runoff events (e.g. >3.0” in a 24-hour period). One inspection shall occur immediately following the winter months after snow has melted. Any accumulated debris and sediments shall be removed. d. Check draining time of vegetative roof annually. Check within 72 hours after a minimum one inch rain event. If there is no standing water, infiltration is acceptable. If draining time is excessive, quantitatively determine infiltration rate. Use a double ring

Form MD-100 February 2014 infiltrometer or monitor drop in water level after a significant storm. If infiltration rate <0.5 in. /hour, remedial action shall be taken. e. Perform a soil test for nutrients and ph every spring and amend the growing media as recommend by the testing agency. f. During the spring and summer months bi-weekly weeding shall be performed and weeds shall be removed. g. During extreme durations of heat and drought watering may be necessary. h. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

11. Roof Gutters:

a. Remove accumulated debris and inspect for damage. Any damage should be repaired as required.

12. Groundwater Pump System:

a. Pump system shall be inspected for proper operation including all connections and force mains. b. The backup generator and electrical system must be inspected for proper operation by an electrician. c. Sump of the pump chamber shall be cleared of all debris and silt. d. The approved pump model is: e. The existing pump can only be replaced with a pump matching the specifications of the existing pump listed above. A change to a different pump must be approved by the Engineering Division. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

13. Stormwater Pump System:

a. Pump system shall be inspected for proper operation including all connections and force mains. b. The backup generator and electrical system must be inspected for proper operation by an electrician. c. Sump of the pump chamber shall be cleared of all debris and silt. d. The approved pump model is: e. The existing pump can only be replaced with a pump matching the specifications of the existing pump listed above. A change to a different pump must be approved by the Engineering Division. f. Any additional maintenance required per the manufacturer’s specifications shall also be completed.

Disposal of Debris and Sediment:

All debris and sediment removed from the stormwater structures and bioretention/biofiltration basins shall be disposed of legally. There shall be no dumping of silt or debris into or in proximity to any inland or tidal wetlands.

Maintenance Records:

The Owners(s) must maintain all records (logs, invoices, reports, data, etc.) and have them readily available for inspection at all times.

Form MD-100 February 2014 Operations and Maintenance Log (Page 1 of 5) (Property Address) (Date) ______

Type of Inspection:  Spring  Fall  Other

Inspector’s Name:______Date of Inspection:______

Affiliation:______Phone #:______

Catch Basins & Drainage Inlets:

 Has accumulated debris been removed from grates?  Yes  No  N/A  Do any basins require additional repair? (identify below):  Yes  No  N/A  Have sumps been cleaned of sediment?  Yes  No  N/A

Notes:

Storm Drainage Piping and Manholes/Junction Boxes:

 Has accumulated debris been removed?  Yes  No  N/A  Do any manholes require additional repair? (identify below):  Yes  No  N/A  Is there any evidence of stormwater piping failure?  Yes  No  N/A  Has a comprehensive video inspection been completed?  Yes  No  N/A

Notes:

Stormwater Control Structures:

 Has accumulated debris been removed?  Yes  No  N/A  Are any repairs required? (identify below):  Yes  No  N/A  Have orifices and weirs been cleaned of debris?  Yes  No  N/A

Notes:

Form MD-100 February 2014 Operations and Maintenance Log (Page 2 of 5) (Property Address) (Date)

Hydrodynamic Separators:

 Has accumulated debris been removed?  Yes  No  N/A  Does unit require additional repair? (identify below):  Yes  No  N/A  Has unit been cleaned of sediment?  Yes  No  N/A

Notes:

Drainage Outfalls/Splash Pads/Scour Holes/Level Spreaders:

 Have all drainage outlets been cleared of debris?  Yes  No  N/A  Have all outlet protections been inspected/repaired?  Yes  No  N/A  Have all erosion issues been repaired?  Yes  No  N/A

Notes:

Bioretention/Biofiltration Basins/Rain Gardens:

 Have basins been cleared of debris/sediments?  Yes  No  N/A  Have draining times of basins been verified?  Yes  No  N/A  Has vegetation been mowed (twice/year max.)?  Yes  No  N/A  Has plantings and mulch been replaced (twice/year)?  Yes  No  N/A

Notes:

Drywells and Infiltration Systems:

 Have units been cleared of debris/sediments?  Yes  No  N/A  Do units require additional repair? (identify below):  Yes  No  N/A  Has draining times of system been verified?  Yes  No  N/A

Notes:

Porous Pavement:

 Has pavement been vacuumed?  Yes  No  N/A  Has draining times been verified?  Yes  No  N/A

Notes:

Gravel Pavement:

 Has pavement been graded and additional gravel added?  Yes  No  N/A  Has draining times been verified?  Yes  No  N/A

Notes:

Vegetative Roof:

 Have trays been cleared of debris/sediments?  Yes  No  N/A  Have draining times of trays been verified?  Yes  No  N/A  Has vegetation been weeded (bi-weekly)  Yes  No  N/A  Have roof drains been inspected and cleared of debris  Yes  No  N/A

Notes:

Roof Gutters:

 Has accumulated debris been removed from gutters?  Yes  No  N/A  Do any gutters require additional repair? (identify below):  Yes  No  N/A

Notes:

Groundwater Pump System:

 Has the electrical connections been inspected?  Yes  No  N/A  Has the electrical connections for the generator been inspected?  Yes  No  N/A  Has the generator been exercised?  Yes  No  N/A  Has the sump been cleaned? (identify below):  Yes  No  N/A

Notes:

Stormwater Pump System:

 Has the electrical connections been inspected?  Yes  No  N/A  Has the electrical connections for the generator been inspected?  Yes  No  N/A  Has the generator been exercised?  Yes  No  N/A  Has the sump been cleaned? (identify below):  Yes  No  N/A

Notes:

Please make additional notes/observations and particular concerns below. Also record any additional maintenance that has been performed:

______

Signature of Inspector: Date:

Form MD-100 February 2014